Positioner for precisely moving an E-block of a disk drive

ABSTRACT

A positioner ( 20 ) for a disk drive ( 10 ) that includes a magnet assembly ( 52 ), a conductor assembly ( 54 ), and a control system ( 22 ) is provided herein. The magnet assembly ( 52 ) includes a pair of magnet arrays ( 56 A) ( 56 B) and a pair of spaced apart flux return plates ( 75 A) ( 75 B). The conductor assembly ( 54 ) includes at least a first coil array ( 80 ) and a second coil array ( 82 ) that are substantially co-planar. The control system ( 22 ) directs current to electrically excite the coil arrays ( 80 ) ( 82 ) to maintain a data transducer ( 50 ) on a target track ( 32 ) of a storage disk ( 28 ).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.09/769,005, filed Jan. 23, 2001 now U.S. Pat. No. 6,768,614.

FIELD OF THE INVENTION

The present invention relates generally to disk drives for storing andretrieving data. More specifically, the present invention relates to apositioner for a disk drive that precisely positions and maintains adata transducer on a target track of a storage disk. Further, thepositioner is uniquely designed to minimize wear on an E-block andthereby decrease the likelihood of track mis-registration.

BACKGROUND

Disk drives are widely used in computers and data processing systems forstoring information in digital form. These disk drives commonly use oneor more rotating storage disks to store data in digital form. Eachstorage disk typically includes a data storage surface on each side ofthe storage disk. These storage surfaces are divided into a plurality ofnarrow, annular regions of different radii, commonly referred to as“tracks”. Typically, a head stack assembly having a positioner and anE-block is used to position a data transducer of a transducer assemblyproximate each data storage surface of each storage disk. The datatransducer transfers information to and from the storage disk whenprecisely positioned on the appropriate track of the storage surface.The transducer assembly also includes a load beam and a suspension forsupporting the data transducer.

The need for increased storage capacity and compact construction of thedisk drive has led to the use of disks having increased track density ordecreased track pitch, i.e., more tracks per inch. As the tracks perinch increase, the ability to maintain the data transducer on a targettrack becomes more difficult. More specifically, as track densityincreases, it is necessary to reduce positioning error of the datatransducer proportionally. With these systems, the accurate and stablepositioning of the data transducer proximate the appropriate track iscritical to the accurate transfer and/or retrieval of information fromthe rotating storage disks.

One attempt to improve positioning accuracy includes increasing theservo bandwidth of the positioner. Unfortunately, as the bandwidth ofthe positioner is increased, it approaches a resonant frequency of thehead stack assembly and it becomes more difficult to keep the positionerstable.

Another attempt to raise servo bandwidth of the head stack assemblyincludes securing a pair of piezoelectric motors to the load beam ofeach transducer assembly. This configuration is known in the industry asa dual stage actuator. Unfortunately, existing dual actuators are notentirely satisfactory. For example, existing dual stage actuatorstypically add substantial cost to the disk drive because everytransducer assembly includes a pair of piezoelectric motors. Further,the drive electronics for the dual stage actuator is more complex due tothe need to generate positive and negative voltages well beyond thesupply rails.

Yet another attempt to improve positioning accuracy includes utilizing apositioner having a pair of vertically offset coil arrays. Thispositioner design eliminates the major resonant frequency and allows forhigher servo bandwidth by the positioner. Unfortunately, the verticallyoffset coil arrays generate a twisting moment on the E-block that cangreatly influence the accuracy of positioning and can cause wear on theE-block.

In light of the above, it is an object of the present invention tosignificantly increase the servo bandwidth of the head stack assembly.Another object of the present invention is to provide a positioner thataccurately positions the data transducers. Still another object of thepresent invention is to provide a positioner that prevents the excitingof the system mode at an E-block pivot center. Yet another object of thepresent invention is to increase servo bandwidth without the use ofpiezoelectric motors on each transducer assembly. Yet another object ofthe present invention is to reduce the cost of manufacturing a highdensity disk drive.

SUMMARY

The present invention is directed to a positioner for a head stackassembly of a disk drive. The disk drive includes one or more storagedisks. The head stack assembly also includes an E-block, and one or moredata transducers. The positioner moves the E-block and the datatransducers relative to the storage disks of the disk drive. Morespecifically, the positioner moves the E-block and the data transducerto a target track of the storage disk. Additionally, the positioneraccurately maintains the data transducer on the target track of thestorage disk.

As provided herein, the positioner includes a magnet assembly, aconductor assembly, and a control system. The conductor assemblyincludes a first coil array and a second coil array that are positionednear the magnet assembly. The control system electrically excites thecoil arrays to interact with the magnet assembly. Uniquely, the firstcoil array and the second coil array are substantially coplanar. As aresult of this design, the positioner avoids the exciting of the majorsystem mode at an E-block pivot center and the servo bandwidth of thepositioner can be increased. Further, the accuracy in which thepositioner positions the data transducer is increased. Moreover, thecoplanar coil arrays do not generate a twisting moment on the E-blockthat can influence the accuracy of the positioner.

As used herein, the term “seek mode” refers to when the positioner ismoving the E-block relative to the storage disks to position the datatransducer onto the target track. Additionally, the term “on-track mode”refers to when the positioner is maintaining the data transducer on thetarget track.

A number of alternate embodiments of the positioner are provided herein.In a first embodiment, the first coil array encircles the second coilarray. In this design, in seek mode, the control system electricallyexcites the first coil array to move the E-block, and the datatransducer, relative to a storage disk to seek the target track on astorage disk. Subsequently, in the on-track mode, the control systemelectrically excites both the first coil array and the second coil arrayto generate opposed forces that maintain the data transducer on thetarget track of the storage disk. The opposed forces of the first andsecond coil arrays prevent exciting of the system mode of the head stackassembly.

In a second embodiment, the second coil array is positioned adjacent toand alongside of the first coil array. In this design, the first coilarray is located closer to the E-block than the second coil array. Inthis design, in the seek mode, the control system electrically excitesboth coil arrays to move the data transducer to the target track.Alternately, in the on-track mode, the control system again electricallyexcites both the first coil array and the second coil array. In thismode, the coil arrays are electrically excited to generate substantiallysimilar magnitude force but in opposite directions in order to maintainthe data transducer on the target track.

In yet another embodiment, the positioner additionally includes a thirdcoil array that is substantially co-planar with the first and secondcoil arrays. In this design, the first coil array encircles the secondcoil array and the third coil array. Further, the second coil array andthe third coil array are positioned side by side. In this design, whenthe positioner is in “seek” mode, the control system electricallyexcites the first coil array to move the E-block so that the datatransducer is positioned on the target track. Subsequently, in the“on-track” mode, the control system electrically excites the second coilarray and the third coil array to maintain the data transducer on thetarget track.

The present invention is also directed to a disk drive and a method forretrieving data from a target track on a rotating storage disk of a diskdrive.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of this invention, as well as the invention itself,both as to its structure and its operation, will be best understood fromthe accompanying drawings, taken in conjunction with the accompanyingdescription, in which similar reference characters refer to similarparts, and in which:

FIG. 1 is a perspective view of a disk drive having features of thepresent invention;

FIG. 2 is a rear view of a positioner having features of the presentinvention;

FIG. 3A is a top view of a first embodiment of a coil set havingfeatures of the present invention;

FIG. 3B is a force diagram of the coil set illustrated in FIG. 3A;

FIG. 4A is a top view of a second embodiment of a coil set havingfeatures of the present invention;

FIG. 4B is a force diagram of the coil set illustrated in FIG. 4A;

FIG. 5A is a top view of a third embodiment of a portion of apositioner, an E-block and a transducer assembly;

FIG. 5B is a force diagram of the embodiment illustrated in FIG. 5A whenthe positioner is in a “seek” mode;

FIG. 5C is a force diagram of the embodiment illustrated in FIG. 5A whenthe positioner is in an “on-track” mode;

FIG. 6A is a top view of a fourth embodiment of a coil set havingfeatures of the present invention; and

FIG. 6B is a force diagram of the coil set illustrated in FIG. 6A.

DESCRIPTION

Referring initially to FIG. 1, a disk drive 10 according to the presentinvention includes (i) a drive housing 12, (ii) a disk assembly 14,(iii) a head stack assembly 15 including an E-block 16, one or moretransducer assemblies 18, and a positioner 20, and (iv) a control system22. As provided herein, the positioner 20 positions the transducerassemblies 18 with improved accuracy, avoids exciting the major systemmode of the head stack assembly 15, and has a higher servo bandwidth.

A detailed description of the various components of a disk drive 10 isprovided in U.S. Pat. No. 5,208,712, issued to Hatch et al., andassigned to Maxtor Corporation, the assignee of the present invention.The contents of U.S. Pat. No. 5,208,712 are incorporated herein byreference. Accordingly, only the structural aspects of a disk drive 10that are particularly significant to the present invention; are providedin detail herein.

The drive housing 12 retains the various components of the disk drive10. The drive housing 12, illustrated in FIG. 1, includes a base 24 andfour (4) side walls 26. A typical drive housing 12 also includes a cover(not shown) that is spaced apart from the base 24 by the side walls 26.The drive housing 12 is typically installed in the case of a computer(not shown) or a word processor (not shown).

The disk assembly 14 includes one or more storage disks 28 that storedata in a form that can be subsequently retrieved if necessary. Magneticstorage disks 28 are commonly used to store data in digital form. Forconservation of space, each storage disk 28 preferably includes a datastorage surface 30 on each side of the storage disk 28. These storagesurfaces 30 are typically divided into a plurality of narrow annularregions of different radii, commonly referred to as “tracks.” Thepositioner 20 provided herein allows for the use of storage disks 28having higher track densities. The storage disks 28 are manufactured byways known to those skilled in the art.

A target track 32 that contains the desired data (not shown) isillustrated in FIG. 1 on the top storage surface 30 on the top storagedisk 28. It should be noted that the target track 32 illustrated in FIG.1 is for reference and that any of the tracks on any of the storagedisks 28 can be the target track 32.

Depending upon the design of the disk drive 10, any number of storagedisks 28 can be used with the disk drive 10. For example, the disk drive10 can include one (1), two (2), three (3), six (6), nine (9), or twelve(12) storage disks 28. For two-sided storage disks 28, the disks 28 arespaced apart a sufficient distance so that at least one (1) transducerassembly 18 can be positioned proximate each of the storage surfaces 30of adjacent storage disks 28. To conserve space, a centerline (notshown) of consecutive disks 28 provides disks 28 typically spaced apartbetween about one millimeter (1.0 mm) to three millimeters (3.0 mm).

The storage disks 28 are mounted on a disk spindle 34 that is mounted toa spindle shaft (not shown). The spindle shaft is secured to the base24. The disk spindle 34 rotates on a disk axis (not shown) relative tothe spindle shaft on a spindle bearing assembly (not shown). Typically,the disk spindle 34 and the storage disks 28 are rotated about the diskaxis at a predetermined angular velocity by a spindle motor (not shown).

The rotation rate of the storage disks 28 varies according to the designof the disk drive 10. Presently, disk drives 10 utilize disks 28 rotatedat an angular velocity of between about 4,500 RPM to 10,000 RPM. It isanticipated that technological advances will allow for disk drives 10having storage disks 28 which rotate at higher speeds, such as about15,000 or more RPM.

As can best be seen with reference to FIG. 1, the E-block 16 includes anactuator hub 36 and a plurality of parallel actuator arms 38 that areattached to and cantilever from the actuator hub 36. In the embodimentillustrated in FIG. 1, the actuator hub 36 is substantially tubular andcan be mounted to an actuator shaft 40. The actuator hub 36 rotates onan E-block pivot center 41 relative to the actuator shaft 40 on anactuator bearing assembly (not shown).

The actuator arms 38 move with the actuator hub 36 and position thetransducer assemblies 18 between the storage disks 26, proximate thedata storage surfaces 30. Each actuator arm 38 includes a proximalsection 42 that is secured to the actuator hub 36 and a distal section44 that cantilevers away from the actuator hub 36. The spacing of theactuator arms 38 varies according to the spacing of the storage disks28. The distance between consecutive actuator arms 38 is typicallybetween about one millimeter (1 mm) to three millimeters (3 mm).

The transducer assemblies 18 transfer or transmit information betweenthe computer (not shown) or word processor (not shown) and the storagedisks 28. Typically, each transducer assembly 18 includes a load beam46, a flexure 48, and a data transducer 50. The load beam 46 attachesthe flexure 48 and the data transducer 50 to the E-block 16. Preferably,each load beam 46 is flexible in a direction perpendicular to thestorage disk 28 and acts as a spring for supporting the data transducer50.

Each flexure 48 is used to attach one (1) of the data transducers 50 toone (1) of the load beams 46. Typically, each flexure 48 includes aplurality of conductive flexure traces (not shown) that are electricallyconnected to the data transducer 50. Each flexure 48 is subsequentlyattached to a flex circuit (not shown) that electrically connects theflexures 48 to the disk drive 10.

Each data transducer 50 interacts with one (1) of the storage disks 28to access or transfer information to the storage disk 28. For a magneticstorage disk 28, the data transducer 50 is commonly referred to as aread/write head.

The positioner 20 precisely moves and positions the E-block 16 and thedata transducers 50 relative to the storage disks 28. The design of thepositioner 20 can varied in accordance with the teachings providedherein. A number of alternate embodiments are provided herein. In eachembodiment, referring to FIG. 2, the positioner 20 includes a magnetassembly 52 and a conductor assembly 54. Further, in each embodiment thepositioner 20 positions and maintains the position of the datatransducers 50 with improved accuracy, eliminates the major system modeof the head stack assembly 15, and allows for a higher servo bandwidth.

The magnet assembly 52 includes one or more magnet arrays. In theembodiments provided herein, the magnet assembly 52 includes an uppermagnet array 56A and a lower magnet array 56B that are spaced apart byan air gap 58. Each magnet array 56A, 56B includes one or more magnets.Alternatively, the positioner 20 could include a single magnet array.

In the embodiments illustrated in the Figures, each magnet array 56A,56B is somewhat arc-shaped and includes a substantially flat top surface60, a spaced apart, substantially flat bottom surface 62, an arc shapedinner side 64, an arc shaped outer side 66, and a pair of spaced apartradial sides 68. A transition zone 70 vertically divides the each magnetarray 56A, 56B into a first sector 72 and a second sector 74 which areside-by-side. The transition zone 70 is represented by dashed lines.Each of the sectors 72, 74, when magnetized, has a north pole and asouth pole. The poles of the first and second sectors 72, 74, for theupper magnet array 56A are inverted relative to each other, and thefirst and second sectors 72, 74 for the lower magnet array 56B areinverted relative to each other. Further, (i) the poles of the firstsector 72 of the upper magnet array 56A and poles of the first sector 72of the lower magnet array 56B are opposed and (ii) the poles of thesecond sector 74 of the upper magnet array 56A and poles of the secondsector 74 of the lower magnet array 56B are opposed.

Preferably, the magnet assembly 52 includes an upper flux return plate75A and a spaced apart lower flux return plate 75B. The flux returnplates 75A, 75B serve as a return path for magnetic fields from themagnet arrays 56A, 56B. Each return plate 75A, 75B is preferably made ofa magnetically permeable material such as a soft iron or steel.Typically, the return plates 75A, 75B are secured to the base 24.Further, the upper magnet array 56A is secured to the upper return plate75A and the lower magnet array 56B is secured to the lower return plate75B.

The conductor assembly 54 includes a conductor housing 76, and a coilset 78. In each embodiment, the conductor housing 76 secures the coilset 78 to the E-block 16, with at least a portion of the coil set 78positioned in the air gap 58 between the magnet arrays 56A, 56B. Theconductor housing 76 can be a separate component from the E-block 16 orthe conductor housing 76 can be formed as an integral part of theE-block 16.

The coil set 78 interacts with the magnet assembly 52 to precisely movethe E-block 16 and each data transducer 50 relative to the storage disks28. A number of alternate embodiments of the coil set 78 are providedherein. However, those skilled in the art will recognize that otherembodiments are possible with the teachings provided herein. As anoverview, in each embodiment, the coil set 78 includes a first coilarray 80 and a second coil array 82 that are coplanar. Further, in theembodiment illustrated in FIGS. 3A and 3B, the coil set 78 also includesa third coil array 84 that is coplanar with the first coil array 80 anda second coil array 82. As provided herein, each of the coil arrays 80,82, 84 includes a wire that is wrapped into a plurality of turns orcoils. Because the coil arrays 80, 82, 84 are coplanar, the positioner20 does not generate a twisting moment on the E-block 16 and the size ofthe positioner 20 is not increased.

FIGS. 3A and 3B illustrate a first embodiment of a coil set 78 havingfeatures of the present invention. In this embodiment, the coil set 78includes the first coil array 80, the second coil array 82 and the thirdcoil array 84. In this embodiment, each coil array 80, 82, 84 issomewhat flat, and trapezoidal shaped. Further, in this embodiment, thefirst coil array 80 encircles the second coil array 82 and the thirdcoil array 84. Stated another way, the second coil array 82 and thethird coil array 84 are positioned within the first coil array 80.Moreover, the third coil array 84 and the second coil array 82 arepositioned side-by-side and adjacent to each other. All of the coilarrays 80, 82, 84 are positioned in substantially the same plane.Additionally, the second coil array 82 is positioned closer to theactuator hub 36 (not shown in FIGS. 3A and 3B) and the E-block pivotcenter 41 than the third coil array 84.

The first coil array 80 includes a first left leg 86A, a first right leg86B, a first distal section 86C and a first proximal section 86D.Similarly, the second coil array 82 includes a second left leg 88A, asecond right leg 88B, a second distal section 88C and a second proximalsection 88D. Further, the third coil array 84 includes a third left leg90A, a third right leg 90B, a third distal section 90C and a thirdproximal section 90D. For each respective coil array 80, 82, 84, theproximal section 86D, 88D, 90D is positioned closest to the E-block 16while the distal section 86C, 88C, 90C is positioned farther from theE-block 16. Each distal section 86C, 88C, 90C and each proximal section86D, 88D, 90D is somewhat arc-shaped. Further, each left leg 86A, 88A,90A and each right leg 86B, 88B, 90B is generally straight and ispositioned generally radially from the E-block pivot center 41.

In the embodiment of FIG. 3A, the second coil array 82 is positionedsuch that (i) the second proximal section 88D is near the first proximalsection 86D, (ii) the second left leg 88A is substantially parallel toand adjacent to the first left leg 86A, and (iii) the second right leg88B is substantially parallel to and adjacent to the first right leg86B. The third coil array 84 is positioned so that (i) the thirdproximal section 90D is positioned adjacent the second distal section88C, (ii) the third distal section 90C is adjacent the first distalsection 86C, (iii) the third left leg 90A is generally parallel to andadjacent the first left leg 86A, and (iv) the third right leg 90B issubstantially parallel to and adjacent with the first right leg 86B.

The control system 22 directs current to the coil set 78 to move thecoil set 78 relative to the magnet assembly 52 and the E-block 16relative to the disk assembly 14. The design of the control system 22will depend upon the design of the coil set 78, the desired movement ofthe E-block 16. In each embodiment, the control system 22 directscurrent to at least one of the coil arrays 80, 82, 84 to move theE-block 16 relative to the disk assembly 14. Further, the control system22 independently directs current to at least two of the coil arrays 80,82, 84 to maintain the data transducer 50 on the target track 32. Thecontrol system 22 controls current to the positioner 20 based uponwhether the positioner 20 is in “seek mode” or “on-track mode”. Thecontrol system 22 can include, for example, an individual controller(not shown) for each of the coil arrays 80, 82, 84. Alternatively, asingle controller 22 may control the flow of current in the coil set 78.

In the embodiment illustrated in FIGS. 3A and 3B, in the “seek mode” thecontrol system 22 directs current to the first coil array 80 to move thecoil set 78 relative to the magnet assembly 52 and move the datatransducer 50 relative to the target track 32. In this design, theelectrically excited first coil array 80 interacts with the magnetassembly 52 to create a Lorentz type force that moves the coil set 78relative to the magnet assembly. More specifically, the resultantmagnetic fields of the magnet assembly 52 are such that current passingthrough the first coil array 80 in one direction causes rotation of theactuator arms 38 in one radial direction relative to the disks 28 (suchas the radially outward direction) while reverse current causes reversedirection movement (such as the radially inward direction). Alternately,to decrease the seek time of the positioner 20 while is the seek mode,the control system 22 can also direct current to the second coil array82 and/or the third coil array 84.

In the on-track mode, in FIGS. 3A and 3B, the control system 22independently directs current to the second coil array 82 and the thirdcoil array 84 to maintain the data transducer 50 (not shown in FIGS. 3Aand 3B) on the target track 32 (not shown in FIGS. 3A and 3B). Morespecifically, the control system 22 directs current to the second coilarray 82 and the third coil array 84 so that the Lorentz type forcegenerated by the electrically excited second coil array 82 issubstantially equal and opposite to the Lorentz type force generated bythe electrically excited third coil array 84. As provided herein, thecurrent to the second coil array 82 is opposite in direction to thecurrent directed to the third coil array 84. If the design of the secondcoil array 82 and the third coil array 84 is the same, and the magneticflux is the same, then the magnitude of the current to the second coilarray 82 and the third coil array 84 should be approximately the same.Alternately, magnitude of the current to the second coil array 82 andthe third coil array 84 can be adjusted appropriately so that the forcegenerated by the second coil array 82 is equal and opposite to the forcegenerated by the third coil array 84.

FIG. 3B illustrates the Lorenz-type forces created by the positioner 20when in the positioner 20 is in the on-track mode. When the positioner20 is in “on-track mode”, the sum of the forces generated with respectto the second coil array 82 are equal to and directionally opposite thesum of the forces generated with respect to the third coil array 84. Inthis design, for the second coil array 82, (i) the second left leg 88Aproduces a first force F₁, (ii) the second right leg 88B produces asecond force F₂, (iii) the second distal section 88C produces a thirdforce F₃ and a fourth force F₄, (iv) the second proximal section 88Dproduces a fifth force F₅, and a sixth force F₆. Similarly, for thethird coil array 84 (i) the third left leg 90A produces a seventh forceF₇, (ii) the third right leg 90B produces an eighth force F₈, (iii) thethird distal section 90C produces a ninth force F₉ and a tenth force F₁₀and (iv) the third proximal section 90D produces an eleventh force F₁₁and a twelfth force F₁₂.

In the on track mode, current to the second coil array 82 and the thirdcoil array 84 is controlled so that (i) force F₁ is equal in magnitude,but directionally the opposite of force F₇, resulting in a “forcecouple”, and (ii) F₂ is equal in magnitude, but directionally theopposite of force F₈, again resulting in a force couple. Thus, there isno net reaction force or torque on the actuator hub 36. Moreover, theremaining forces on the tangential parts of the coil arrays 82, 84result in force couples: F₃+F₁₁=F₅+F₉; and F₄+F₁₂=F₁₀+F₆. As aconsequence, no reaction force and lateral force about the actuator hub36 occurs while the positioner is in “on-track mode”.

In this design, because the second coil array 82 and the third coilarray 84 are used to maintain the data transducer 50 on the target track32, the second coil array 82 and the third coil 84 array can be madewith more turns and thinner wire than the first coil array 80.

Further, the control system 22 in the on-track mode can direct currentto the first coil array 80 for low frequencies to correct for bias andrepetitive runout correction. All of the force applied by the first coilarray 80 invokes a reaction force at the E-block pivot center 41, thuspotentially exciting the “system mode”. Therefore, care must be taken toavoid frequency components above a few hundred hertz. The second coilarray 82 and the third coil array 84 should be used to apply as much aspossible of the high frequency components of the seek current. Thisreduces excitation of the system mode and reduces the acoustic radiationcaused by high frequency coupling into the base 24 and cover (not shown)via the actuator hub 36. Possibly the control system 22 will pass thecurrent command through a virtual crossover network thereby explicitlyseparating the current for the second coil array 82 and the third coilarray 84 in the frequency domain.

FIGS. 4A and 4B depict another embodiment of the present invention. Inthis embodiment, the coil set 78 includes the first coil array 80 andthe second coil array 82 which are substantially co-planar. Thepositioning of the first coil array 80 and the second coil array 82 inthis embodiment are substantially similar to the positioning of thefirst coil array 80 and second coil array 82, respectively, shown inFIG. 3A. However, the embodiment of FIG. 4A does not include the thirdcoil array 84.

The control system 22 directs current to the coil set 78 to move thecoil set 78 relative to the magnet assembly 52, the E-block 16 relativeto the disk assembly 14, and the data transducer 50 relative to thestorage disks 28. In this embodiment, the control system 22 directscurrent to at least one of the coil arrays 80, 82 to move the E-block 16relative to the disk assembly 14. Further, the control system 22independently directs current to both of the coil arrays 80, 82 tomaintain the E-block 16 in position with the data transducer 50 on thetarget track 32.

In the embodiment illustrated in FIGS. 4A and 4B, in the seek mode, thecontrol system 22 directs current to the first coil array 80 to move thecoil set 78 relative to the magnet assembly 52 and move the datatransducer 50 to the target track 32. In this design, the electricallyexcited first coil array 80 generates a Lorentz type force that movesthe coil set 78 relative to the magnet assembly 52. Alternately, todecrease the seek time of the positioner 20, the control system 22 canalso direct current to the second coil array 82.

In the on-track mode, the control system 22 independently directscurrent to the second coil array 82 and the first coil array 80 tomaintain the data transducer 50 on the target track 32. Morespecifically, the control system 22 controls current to the second coilarray 82 and the first coil array 80 so that the Lorentz type forcegenerated by the electrically excited second coil array 82 issubstantially equal and opposite to the Lorentz type force generated bythe electrically excited first coil array 80. As provided herein, thecurrent to the second coil array 82 is opposite in direction to thecurrent directed to the first coil array 80. In this embodiment, thedesign of the second coil array 82 and the first coil array 80 are notthe same. Thus, the control system 22 balances the magnitude of thecurrent to the first coil array 80 and the second coil array 82appropriately.

FIG. 4B illustrates the Lorenz-type forces created by the positioner 20when the positioner 20 is in the on-track mode. When the positioner 20is in “on-track mode”, the sum of the forces generated with respect tothe first coil array 80 are equal to and directionally opposite the sumof the forces generated with respect to the second coil array 82. Inthis design, for the first coil array 80, (i) the first left leg 86Aproduces a first force F₁, (ii) the first right leg 86B produces asecond force F₂, (iii) the first distal section 86C and the firstproximal section 86D do not produce a force because these sections 86C,86D, are not positioned between the magnet arrays 56A, 56B. Thus thefirst distal section 86C and the first proximal section 86D do notinteract with the magnetic field. With respect to the second coil array82 (i) the second left leg 88A produces a third force F₃, (ii) thesecond right leg 88B produces a fourth force F₄, (iii) the second distalsection 88C produces a fifth force F₅ and a sixth force F₆ and (iv) thesecond proximal section 88D produces a seventh force F₇ and a eighthforce F₈.

In the on track mode, the control system 22 provides current to thefirst coil array 80 and the second coil array 82. The forces arecontrolled so that (i) force F₁ is equal in magnitude, but directionallythe opposite of force F₃, resulting in a force couple, and (ii) force F₂is equal in magnitude, but directionally the opposite of force F₄, againresulting in a force couple. Thus, there is no net reaction force on theactuator hub 36. Moreover, the remaining forces generated result inforce couples: F₅=F₇; and F₆=F₈. Therefore, no net reaction force isimparted on the actuator hub 36, resulting in less wear on the actuatorhub 36, longer life of the actuator hub 36, and a decreased likelihoodof track mis-registration.

FIG. 5A illustrates yet another embodiment of the present invention. Inthis embodiment, the coil set 78 includes the first coil array 80 andthe second coil array 82. The configuration of the first coil array 80of this embodiment is somewhat similar to that of the first coil array80 depicted in FIGS. 3A and 4A. The second coil array 82 issubstantially co-planar with the first coil array 80, and is encircledby the first coil array 80. The second coil array 82 is generallyrectangular in shape. In this embodiment, the second distal section 88Cis preferably shaped generally as an arc section of a circle with itscenter at the actuator hub 36, and is generally concentric with thefirst distal member 86C. The second legs 88A, 88B are substantiallyparallel to each other, and are substantially parallel to a longitudinalaxis 92 of the E-block 16.

In the embodiment illustrated in FIG. 5A, the control system 22 directscurrent to the first coil array 80 to move the coil set 78 relative tothe magnet assembly 52 and move the data transducer 50 to the targettrack 32. In this design, the electrically excited first coil array 80generates a Lorentz type force that moves the coil set 78 relative tothe magnet assembly 52. Alternatively, to decrease the seek time of thepositioner 20, the control system 22 can also direct current to thesecond coil array 82.

In the on-track mode, as illustrated in FIG. 5C, the control system 22independently directs current to the first coil array 80 and the secondcoil array 82 to maintain the data transducer 50 on the target track 32.More specifically, the control system 22 controls current to the firstcoil array 80 and the second coil array 82 so that the Lorentz typeforce generated by the electrically excited first coil array 80 issubstantially equal and opposite to the Lorentz type force generated bythe electrically excited second coil array 82. As provided herein, thecurrent to the first coil array 80 is opposite in direction to thecurrent directed to the second coil array 82. The magnitude of thecurrent to the first coil array 80 and the second coil array 82 can beadjusted appropriately by the control system 22 to compensate for thedifferences in size of the coil arrays 80, 82.

FIG. 5B illustrates the forces of the coil set 78 with the controlsystem 22 in the seek mode. In this embodiment, the first coil array 80and the second coil array 82 cooperate to move the E-block 16 to atarget track 32 of the storage disk 28. More specifically, the firstleft leg 86A generates a first force F1 having two force vectors F_(1A),F_(1B) which are perpendicular to one another. Similarly, the firstright leg 86B generates a second force F2 having two force vectorsF_(2A), F_(2B) that are perpendicular to one another. Further, thesecond left leg 88A generates a third force F3 and the second right leg88B generates a fourth force F4. In the seek mode, the force F_(1B) fromthe first left leg 86A is equal in magnitude and directionally oppositethe force F_(2B) from the second coil leg 88A resulting in a forcecouple. In contrast, the F_(1A), F_(2A), F3 and F4 forces aresubstantially equal in magnitude, and are substantially directionallysimilar. Therefore, with this embodiment of the positioner 20, in theseek mode, the coils 80, 82, work in concert to move the E-block 16relative to the target track 32 of the storage disk 28.

When the embodiment of the present invention shown in FIG. 5A is in theon-track mode, the first coil array 80 and the second coil array 82oppose each other to maintain the data transducer 50 on the target track32 of the storage disk 28. Referring to FIG. 5C, the forces generated bythe first coil array 80 remain essentially unchanged from the first coilarray 80 forces when the positioner 20 is in “seek mode”. The F3, F4forces generated by the second coil array 82, however, reverse directionin order to oppose the F_(1A), F_(2A) forces of the first coil array 80.The result is a sum total of zero force in the direction perpendicularto the longitudinal axis 92 of the E-block 16. Once again, a forcecouple exists with respect to the F_(1B), F_(2B) forces. The net resultis less wear and longer life for the actuator hub 36, and a decreasedlikelihood of track mis-registration.

FIG. 6A shows still another alternative embodiment of the presentinvention, which includes the first coil array 80 and the second coilarray 82 which are co-planar, and are oriented substantially similar tothe second coil array 82 and third coil array 84, respectively, of FIG.3A. The embodiment shown in FIG. 6A, however, does not include the thirdcoil array 84.

In the embodiment illustrated in FIG. 6A, the control system 22 directscurrent to the first coil array 80 to move the coil set 78 relative tothe magnet assembly 52 and move the data transducer 50 to the targettrack 32. In this design, the electrically excited first coil array 80generates a Lorentz type force that moves the coil set 78 relative tothe magnet assembly 52. Alternatively, to decrease the seek time of thepositioner 20, the control system 22 can also direct current to thesecond coil array 82.

In the on-track mode of this embodiment, the control system 22independently directs current to the first coil array 80 and the secondcoil array 82 to maintain the data transducer 50 on the target track 32.More specifically, the control system 22 controls current to the firstcoil array 80 and the second coil array 82 so that the Lorentz typeforce generated by the electrically excited first coil array 80 issubstantially equal and opposite to the Lorentz type force generated bythe electrically excited second coil array 82. As provided herein, thecurrent to the first coil array 80 is opposite in direction to thecurrent directed to the second coil array 82. The magnitude of thecurrent to the first coil array 80 and the second coil array 82 can beadjusted appropriately by the control system 22 to compensate for thedifferences in size of the coil arrays 80, 82.

FIG. 6B illustrates the Lorenz-type forces created by the positioner 20in the on-track mode. When the positioner 20 is in “on-track mode”, thesum of the forces generated with respect to the second coil array 82 areequal to and directionally opposite the sum of the forces generated withrespect to the first coil array 80. In this design, for the first coilarray 80, (i) the first left leg 86A produces a first force F₁, (ii) thefirst right leg 86B produces a second force F₂, (iii) the first distalsection 86C produces a third force F₃ and a fourth force F₄, and (iv)the first proximal section 86D produces a fifth force F₅, and a sixthforce F₆. Similarly, for the second coil array 82 (i) the second leftleg 88A produces a seventh force F₇, (ii) the second right leg 88Bproduces an eighth force F₈, (iii) the second distal section 88Cproduces a ninth force F₉ and a tenth force F₁₀ and (iv) the secondproximal section 88D produces an eleventh force F₁₁ and a twelfth forceF₁₂.

In the on track mode, current to the first coil array 80 and the secondcoil array 82 is controlled so that (i) force F₁ is equal in magnitude,but directionally the opposite of force F₇, resulting in a force couple,and (ii) force F₂ is equal in magnitude, but directionally the oppositeof force F₈, again resulting in a force couple. Thus, there is no netreaction force or torque on the actuator hub 36. Moreover, the remainingforces on the tangential parts of the coil arrays 80, 82 result in forcecouples: F₃+F₁₁=F₅+F₉; and F₄+F₁₂=F₁₀+F₆. As a consequence, no reactionforce and lateral force about the actuator hub 36 occurs while thepositioner is in the on-track mode.

In the seek mode of this embodiment, the conductor assembly 54 depictedin FIG. 6A will maintain the force couples of F₃+F₁₁=F₅+F₉; andF₄+F₁₂=F₁₀+F₆. However, the forces F₁, F₂, F₇ and F₈ will cooperate tomove the E-block 16 to a target track 32 on a storage disk 28. Toaccomplish this, the control system 22 reverses the current flowing ineither the first coil array 80 or the second coil array 82. Thus, eitherthe forces F₁ and F₂ from the first coil array 80 will reversedirection, or the forces F₇ and F₈ from the second coil array 82 willreverse direction, such that all forces, F₁, F₂, F₇ and F₈ will besubstantially directionally aligned to move the E-block 16 relative tothe target track 32 of a storage disk 28.

While the particular positioner 20 and disk drive 10 as herein shown anddisclosed in detail is fully capable of attaining the objectives andproviding the advantages herein before stated, it is to be understoodthat it is merely illustrative of the presently preferred embodiments ofthe invention and that no limitations are intended to the details ofconstruction or design herein shown other than as described in theappended claims.

1. A positioner for moving an E-block and a data transducer of a diskdrive relative to a storage disk of the disk drive, the positionercomprising: a magnet assembly producing a magnetic field; and aconductor assembly that couples to the E-block and is positioned nearthe magnet assembly, the conductor assembly including (i) a first coilarray, and (ii) a second coil array positioned in substantially the sameplane as the first coil array, wherein the first coil array includes afirst left leg, a first right leg, a first distal section and a firstproximal section, the first left leg extends between the first distalsection and the first proximal section, the first right leg extendsbetween the first distal section and the first proximal section and isspaced from the first left leg, the first distal section extends betweenthe first left leg and the first right leg, and the first proximalsection extends between the first left leg and the first right leg andis spaced from the first distal section and is closer to the E-blockthan the first distal section is to the E-block, the second coil arrayincludes a second left leg, a second right leg, a second distal sectionand a second proximal section, the second left leg extends between thesecond distal section and the second proximal section, the second rightleg extends between the second distal section and the second proximalsection and is spaced from the second left leg, the second distalsection extends between the second left leg and the second right leg,and the second proximal section extends between the second left leg andthe second right leg and is spaced from the second distal section and iscloser to the E-block than the second distal section is to the E-block,and the first coil array encircles the second coil array, and the secondleft leg is parallel to the second right leg.
 2. The positioner of claim1 wherein the first left leg and the first right leg interact with themagnetic field and the first distal section and the first proximalsection do not interact with the magnetic field; and the second leftleg, the second right leg, second distal section and the second proximalsection interact with the magnetic field.
 3. The positioner of claim 1wherein the first left leg, the first right leg and the first proximalsection are straight, and the first distal section is arc-shaped.
 4. Thepositioner of claim 1 wherein the second left leg, the second right legand the proximal section are straight, and the second distal section isarc-shaped.
 5. The positioner of claim 1 wherein the first left leg, thefirst right leg and the first proximal section are straight, and thefirst distal section is arc-shaped; and the second left leg, the secondright leg and the proximal section are straight, and the second distalsection is arc-shaped.
 6. The positioner of claim 1 wherein the firstleft leg is not parallel to the first right leg.
 7. The positioner ofclaim 1 wherein the first left leg is not parallel to the second leftleg.
 8. The positioner of claim 1 wherein the first right leg is notparallel to the second right leg.
 9. The positioner of claim 1 whereinthe first left leg and the first right leg are not parallel to thesecond left leg and the second right leg and are not parallel to eachother.
 10. The positioner of claim 1 wherein the first distal section isadjacent to the second distal section, and the first proximal section isadjacent to the second proximal section.
 11. The positioner of claim 1wherein the first proximal section is parallel to and adjacent to thesecond proximal section.
 12. The positioner of claim 1 wherein the firstdistal section is adjacent to the second distal section, and the firstproximal section is parallel to and adjacent to the second proximalsection.
 13. The positioner of claim 1 wherein the first left leg iscloser to the second proximal section than the second distal section.14. The positioner of claim 1 wherein the first right leg is closer tothe second proximal section than the second distal section.
 15. Thepositioner of claim 1 wherein the first left leg is closer to the secondproximal section than the second distal section; and the first right legis closer to the second proximal section than the second distal section.16. The positioner of claim 1 wherein the first distal sectionintersects an imaginary line that extends through and is orthogonal tothe second left leg and the second right leg.
 17. The positioner ofclaim 1 wherein the first left leg, the first right leg and the firstproximal section are straight, and the first distal section isarc-shaped; the second left leg, the second right leg and the proximalsection are straight, and the second distal section is arc-shaped; thefirst left leg is not parallel to the first right leg; the first leftleg is not parallel to the second left leg; the first right leg is notparallel to the second right leg; the first distal section is adjacentto the second distal section; and the first proximal section is parallelto and adjacent to the second proximal section.
 18. The positioner ofclaim 1 wherein the first left leg is not parallel to the first rightleg; the first left leg is not parallel to the second left leg; thefirst right leg is not parallel to the second right leg; the firstdistal section is adjacent to the second distal section; the firstproximal section is parallel to and adjacent to the second proximalsection; the first left leg is closer to the second proximal sectionthan the second distal section; and the first right leg is closer to thesecond proximal section than the second distal section.
 19. Thepositioner of claim 1 wherein the first left leg, the first right legand the first proximal section are straight, and the first distalsection is arc-shaped; the second left leg, the second right leg and theproximal section are straight, and the second distal section isarc-shaped; the first left leg is not parallel to the first right leg;the first left leg is not parallel to the second left leg; the firstright leg is not parallel to the second right leg; the first distalsection is adjacent to the second distal section; the first proximalsection is parallel to and adjacent to the second proximal section; thefirst left leg is closer to the second proximal section than the seconddistal section; and the first right leg is closer to the second proximalsection than the second distal section.
 20. The positioner of claim 19wherein the first distal section intersects an imaginary line thatextends through and is orthogonal to the second left leg and the secondright leg.
 21. A positioner for moving an E-block and a data transducerof a disk drive relative to a storage disk of the disk drive, thepositioner comprising: a magnet assembly producing a magnetic field; anda conductor assembly that couples to the E-block and is positioned nearthe magnet assembly, the conductor assembly including (i) a first coilarray, and (ii) a second coil array positioned in substantially the sameplane as the first coil array, wherein the first coil array includes afirst left leg, a first right leg, a first distal section and a firstproximal section, the first left leg extends between the first distalsection and the first proximal section, the first right leg extendsbetween the first distal section and the first proximal section and isspaced from the first left leg, the first distal section extends betweenthe first left leg and the first right leg, and the first proximalsection extends between the first left leg and the first right leg andis spaced from the first distal section and is closer to the E-blockthan the first distal section is to the E-block, the second coil arrayincludes a second left leg, a second right leg, a second distal sectionand a second proximal section, the second left leg extends between thesecond distal section and the second proximal section, the second rightleg extends between the second distal section and the second proximalsection and is spaced from the second left leg, the second distalsection extends between the second left leg and the second right leg,and the second proximal section extends between the second left leg andthe second right leg and is spaced from the second distal section and iscloser to the E-block than the second distal section is to the E-block,and the first coil array encircles the second coil array, and the secondleft leg and the second right leg are parallel to a longitudinal axis ofthe E-block.
 22. The positioner of claim 21 wherein the first left legand the first right leg interact with the magnetic field and the firstdistal section and the first proximal section do not interact with themagnetic field; and the second left leg, the second right leg, seconddistal section and the second proximal section interact with themagnetic field.
 23. The positioner of claim 22 wherein the first leftleg, the first right leg and the first proximal section are straight,and the first distal section is arc-shaped.
 24. The positioner of claim22 wherein the second left leg, the second right leg and the proximalsection are straight, and the second distal section is arc-shaped. 25.The positioner of claim 22 wherein the first left leg, the first rightleg and the first proximal section are straight, and the first distalsection is arc-shaped; and the second left leg, the second right leg andthe proximal section are straight, and the second distal section isarc-shaped.
 26. The positioner of claim 22 wherein the first left leg isnot parallel to the first right leg.
 27. The positioner of claim 22wherein the first left leg is not parallel to the second left leg. 28.The positioner of claim 22 wherein the first right leg is not parallelto the second right leg.
 29. The positioner of claim 22 wherein thefirst left leg and the first right leg are not parallel to the secondleft leg and the second right leg and are not parallel to each other.30. The positioner of claim 21 wherein the first distal section isadjacent to the second distal section, and the first proximal section isadjacent to the second proximal section.
 31. The positioner of claim 21wherein the first proximal section is parallel to and adjacent to thesecond proximal section.
 32. The positioner of claim 21 wherein thefirst distal section is adjacent to the second distal section, and thefirst proximal section is parallel to and adjacent to the secondproximal section.
 33. The positioner of claim 21 wherein the first leftleg is closer to the second proximal section than the second distalsection.
 34. The positioner of claim 21 wherein the first right leg iscloser to the second proximal section than the second distal section.35. The positioner of claim 21 wherein the first left leg is closer tothe second proximal section than the second distal section; and thefirst right leg is closer to the second proximal section than the seconddistal section.
 36. The positioner of claim 21 wherein the first distalsection intersects an imaginary line that extends through and isorthogonal to the second left leg and the second right leg.
 37. Thepositioner of claim 21 wherein the first left leg, the first right legand the first proximal section are straight, and the first distalsection is arc-shaped; the second left leg, the second right leg and theproximal section are straight, and the second distal section isarc-shaped; the first left leg is not parallel to the first right leg;the first left leg is not parallel to the second left leg; the firstright leg is not parallel to the second right leg; the first distalsection is adjacent to the second distal section; and the first proximalsection is parallel to and adjacent to the second proximal section. 38.The positioner of claim 21 wherein the first left leg is not parallel tothe first right leg; the first left leg is not parallel to the secondleft leg; the first right leg is not parallel to the second right leg;the first distal section is adjacent to the second distal section; thefirst proximal section is parallel to and adjacent to the secondproximal section; the first left leg is closer to the second proximalsection than the second distal section; and the first right leg iscloser to the second proximal section than the second distal section.39. The positioner of claim 21 wherein the first left leg, the firstright leg and the first proximal section are straight, and the firstdistal section is arc-shaped; the second left leg, the second right legand the proximal section are straight, and the second distal section isarc-shaped; the first left leg is not parallel to the first right leg;the first left leg is not parallel to the second left leg; the firstright leg is not parallel to the second right leg; the first distalsection is adjacent to the second distal section; the first proximalsection is parallel to and adjacent to the second proximal section; thefirst left leg is closer to the second proximal section than the seconddistal section; and the first right leg is closer to the second proximalsection than the second distal section.
 40. The positioner of claim 39wherein the first distal section intersects an imaginary line thatextends through and is orthogonal to the second left leg and the secondright leg.